Heads of state and government have arrived in Durban, South Africa, raising hopes U.N. climate-change talks will gain momentum. While expectations for a major deal remain low, world leaders are urging all parties to work together to confront the urgent threat posed by global warming.

South African President Jacob Zuma told assembled delegates at the U.N. climate conference in Durban the world is looking to its leaders to overcome their differences and to come up with solutions to combat climate change.

?The problem is that we all agreed that the Earth is in danger," said Zuma. "We all agreed that in fact we must do something about it. We also all agreed that the problem is when we have got to say, 'What is it? How?' I think we must overcome that hurdle.?

Zuma summed up progress at the talks, which have been slowed by differences between governments on key agreements, including whether to accept a second commitment period for the Kyoto Protocol - a legally binding mandate to cut carbon emissions - or to adopt a ?roadmap? to a new global pact.

But several parties that had enacted the Kyoto protocol have indicated they will not sign on for another term, including Japan, Russia and Canada. The United States never adopted the agreement and has ruled out any legally binding deals for now.

Underscoring the low expectations among delegates going into the talks, U.N. Secretary General Ban Ki-moon delivered a sobering message.

?It may be true, as many say, the ultimate goal of a comprehensive and binding climate change agreement may be beyond our reach for now," said Ban. "Yet let me emphasize, none of these uncertainties should prevent us from taking real progress here in Durban.?

Ban said achieving progress at the talks is like riding a bicycle - you stay upright and keep moving forward as long as you maintain momentum.

Many delegates hope Durban will produce an agreement on the Green Climate Fund, which is an initiative hatched at the last climate summit in Cancun, Mexico, to provide developing countries with money to invest in projects that reduce the impact of climate change.

Some countries say they are still waiting for funding from the so-called Fast Start program established at the previous conference in Copenhagen.

Speaking on behalf of the African Union, Ethiopian Prime Minister Meles Zenawi said resolving these funding issues is of ?utmost importance? to Africans.

?We are already severely affected by the climate change, as a result of which the lives of millions of Africans is already at stake as the extraordinary drought in the Horn of Africa shows," said Zenawi. "We are therefore deeply disappointed that the Fast Track funding promised to us in Copenhagen has to a large extent failed to materialize. This puts the credibility of the whole process at risk in the eyes of the peoples of our continent"

One country's leader has refused to accept that conference participants might shift their focus away from stopping the emissions blamed for global warming, and simply find ways to adapt to climate change.

?Already communities in our islands have been forced to flee their homes to escape rising seas, and unless bold action is taken, much of my region could be rendered uninhabitable within our grandchildren's lifetime," said Sprent Dabridow, the president of the island nation of Nauru.